WO2020015229A1

WO2020015229A1 - Static dual-shaft shoulder friction stir welding tool having auxiliary pull rope device and method for welding butt-welded seam

Info

Publication number: WO2020015229A1
Application number: PCT/CN2018/112406
Authority: WO
Inventors: 倪平涛
Original assignee: 倪平涛
Priority date: 2018-07-15
Filing date: 2018-10-29
Publication date: 2020-01-23
Also published as: CN109434270A; CN109434270B

Abstract

A static dual-shaft shoulder friction stir welding tool having an auxiliary pull rope device and a method for welding a lineal or approximately lineal smooth curve butt-welded seam. For the lineal butt-welded seam of a flat plate and a curved plate, two static shaft shoulders (6, 8) in the same shape as that of a contact surfaces are used. A pull rope (14, 27) is additionally provided on each shaft shoulder (6, 8). The pull force of each pull rope (14, 27) is equal to a half of the sum of dry frictional resistance generated by individual shaft shoulder (6, 8) with the friction surface of a workpiece, and forward resistance, generated by the workpiece, caused to a welding pin (1). The main body of the welding pin (1) is made as much as possible to approximately bear only the pure torsion generated due to rotation, so that the pressure condition of the welding pin (1) is greatly improved, and there is always the effect of the pull force of the pull rope (14, 27) on the shaft shoulder (6, 8) and the welding pin (1). By means of such a pull force, a slide plate (16) can be driven by means of the traveling device of the mobile base (25) of a mobile gantry or mobile platform or welding robot, then two shaft shoulder pull ropes (14, 27) are driven by the slide plate (16), and the slide plate (16) and the two pull ropes (14, 27) go forward together. The slide plate (16) can be driven by a motor, then the two shaft shoulder pull ropes (14, 27) and the pull rope (32) of the mobile base (25) of the mobile gantry or mobile platform or welding robot are driven by the slide plate (16), and the slide plate (16) and the three pull ropes (14, 27, 32) go forward together.

Description

Static double-axle shoulder friction stir welding stirrer with auxiliary drawstring device and method for welding butt weld

Technical field:

The present invention integrates the advantages of stationary friction stir welding with stationary shoulders and general friction stir welding with double shoulders. A static twin shaft shoulder stirring head with an auxiliary drawstring device and a butt welding with a straight line and a smooth curve close to a straight line are proposed. The seam method is particularly suitable for welding of medium and thick plates, and it can also be used for welding of thin plates. The fields involved are various types of rail vehicles (including maglev vehicles), ships, various types of automobiles (including tank cars), bridges (including pedestrian bridges), building boards, flat plates and curved plates in aerospace. Welding of butt welds on straight lines and smooth curves close to straight lines.

Background technique:

Friction Stir Welding (FSW) is a new solid-phase welding technology, which was invented by the British Welding Institute in 1991. Friction stir welding technology is known as the most revolutionary welding technology in the 21st century. After more than 20 years of technology research and development and engineering promotion, it has been applied in various fields at home and abroad. Since traditional friction stir welding is accompanied by a large upset pressure during the welding process, it is necessary to strictly clamp the workpiece on the back, and at the same time, a rigid support pad is required on the back, which has caused certain difficulties for its promotion and application; later developed Double shaft shoulder friction stir welding technology, the upper and lower shaft shoulders form mutual support, and the lower shaft shoulder replaces the rigid support pad on the back of the workpiece. This improvement greatly reduces the forging pressure during the welding process and solves the problem that the root is not welded through. Partially resolved burrs and tunnel holes. Later, the friction stir welding with stationary shaft and shoulder was further developed. As long as the welding parameters are suitable, the under-welding and arcing are basically eliminated, and there is basically no large flash, and the performance of the joint is improved. Further improvement. It can be said that in traditional friction stir welding, double shoulder friction stir welding and static shoulder friction stir welding, as long as the welding parameters are appropriate, the joint performance of the static shoulder friction stir welding is the best.

For stationary shoulder friction stir welding, because the shoulder does not rotate, the dry shoulder and the surface of the workpiece are under dry friction. The effect of the workpiece on the torque and forward resistance of the actual working part of the stirring pin itself. The combined force and moment of these forces can easily break the stirring pin or accelerate fatigue damage, making the friction stir welding of stationary shoulders difficult to apply to double shoulder occasions. Especially for welding of medium and thick plates, this problem has not been solved well so far.

Summary of the invention:

The present invention is to solve the needs in actual production, and proposes an integrated static shoulder friction stir welding which can obtain a weld joint with excellent performance and a double shoulder friction stir welding without the advantages of rigid support, and can be welded with high quality and efficiency. Friction stir welding stirrer with auxiliary rope device for thick plates, and a method for simultaneously welding butt welds of two surfaces of medium and thick plates at the same time.

The principle is as follows: ① For linear butt welds, the static shoulder friction stir welding under the prior art conditions is generally replaced by the traditional friction stir welding shoulder with a static shoulder. One static shoulder corresponds to a surface. There is only one dry friction force between the stationary shoulder and the workpiece, and the force condition of the stirring pin is not very complicated, which can meet simple requirements. For welding two surfaces of a flat plate and a curved plate at the same time (such as the longitudinal welding seam of a tank car body), the present invention adopts two stationary shoulders, each shoulder is similar to the existing dual-shoulder friction stir welding, It is also a stationary shoulder corresponding to one surface, and two shoulders corresponding to the two surfaces of the board (the distance between the two shoulders is slightly smaller than the thickness of the wall plate, such as 0.1 to 0.2 mm or other reasonable values, and the existing double The shoulder friction stir welding is roughly the same, the same below). Because there are two dry friction forces, the welding cannot be performed well without adding other devices, especially for medium and thick plates, the stirring pin is easily broken. The invention creatively adds 1 pull rope for each shaft shoulder, and the pulling force of each shaft shoulder rope is equal to the sum of the dry friction resistance generated by the friction surface of the shaft shoulder and the half of the forward resistance generated by the stirring pin by the workpiece, and makes the shaft shoulder The pulling force of the pull rope always exists during the welding process. It seems that the pull rope always pulls the shaft shoulder and the stirring head forward (here is just an image metaphor, in fact it is not). However, the forward speed of the shaft shoulder rope, the shaft shoulder and the stirring needle is equal, and this forward speed is the appropriate welding speed. After moving the gantry or the mobile workpiece platform or the mobile base of the friction stir welding robot, the running device can bear its own forward resistance after moving through the fixed pulley set, and it can also bear the pulling force of the two shoulder shoulder ropes and drive the shaft. Shoulder and pull rope go forward, please refer to Figure 2; it can also be pulled by the pull rope and slide after passing the fixed pulley set and driven by a separate motor. At this time, the mobile gantry or mobile workpiece platform or mobile welding robot's mobile base can be unpowered Devices, which are driven by the motor and the pull rope together with the two shoulder and shoulder ropes through a slide board, see FIG. 4. As for which method to use, it depends on the specific technical conditions and site conditions. Note: When moving the gantry and friction stir mobile welding robot's moving base and moving workpiece platform, the pulling direction of the pull rope is the same, but because the moving direction of the workpiece platform is opposite to the welding forward direction of the weld, the combination of the fixed pulley group is different, below No longer explained. This is the case for straight butt welds, which does not require multiple free welding robots, as long as the welds are parallel to the guide rail. ② For the welding of smooth curved butt welds that are close to a straight line, a welding robot with several degrees of freedom must be used for welding. Generally, the welding robot is moved along the guide rail for welding (there is no gantry), and the robot's base belt automatically moves. Device, or the welding robot is directly installed on the gantry with its own running device, depending on the position of the welding seam and the arm length of the robot; a separate motor can also be used to drive the welding robot through a rope and a fixed pulley, Shoulder pull and shoulder advance. In addition, the welding robot is required to have a welding seam tracking system and a longitudinal sensor (which can be indirectly measured and installed on a suitable arm of the welding robot) to sense the longitudinal force on the stirring head. Because it is a smooth curved butt weld that is close to a straight line, no additional mechanical devices are needed, and the stirring head itself can move in the vertical direction of the rope. If the shoulder moves vertically along the drawstring, it needs to overcome a large frictional resistance and a moment formed by the force, or the stirring needle cannot move at all. However, when the shoulder moves, theoretically, no matter how the shoulder runs, the friction between the shoulder and the workpiece is constant. For a smooth curve butt weld that is close to a straight line, the friction between the friction and the direction of the rope The angle is very small, and its vertical component in the pull rope is very small, while the component of the total friction force in the pull rope direction is borne by the pull rope, and the small frictional component force perpendicular to the pull rope direction is borne by the stirring needle itself. It bears, so the stirring needle when moving forward can easily make the shaft shoulder move vertically along the drawstring.

Just like when friction stir welding is used to weld metals with higher melting points, sometimes it is necessary to use electromagnetic action or laser welding while heating in front of the weld to be welded. This way, the softened weld position can greatly improve the resistance of the stirrer pin. Force condition, this heating device is an auxiliary device for friction stir welding. One of the cores of the present invention, the pull rope and its subsidiary mechanism is also an auxiliary device. By adding the pull rope auxiliary device, the dry friction resistance at the shaft shoulder received by the stirring needle and the stirring needle itself can be simply and skillfully received. The forward resistance is decoupled from the torque part of the stirring needle due to rotation. Try to make the main part of the stirring needle as close as possible to the pure torque effect (of course, it can't actually be done). The force situation has been greatly improved, but the biggest contribution is: a static double-axle shoulder stirring head with a set of auxiliary ropes, which can simultaneously weld two surfaces of the medium and thick plate, and obtain high-quality welded joints.

It should be noted here that the end face of the shoulder is not necessarily a flat surface, and its shape corresponds to the shape of the part to be welded. If the part to be welded is arc-shaped, the end of the shoulder is also arc-shaped with its radius. , And no slot is required on the end face of the shaft shoulder. The shaft-to-shoulder distance corresponding to the two surfaces should be less than the thickness of the plate, so that it produces a certain amount of compression (for example, 0.1 to 0.2 mm), which is similar to the ordinary double-shaft friction stir welding. Only the same shape and size can uniformly compress and play the role of upset pressure. It is possible to greatly reduce the occurrence of flashing. This can give full play to the static shoulder's functions of rubbing and smoothing. Flash

It should also be noted that the two surfaces to be welded are not necessarily the upper and lower horizontal surfaces, they may also be left and right vertical elevations, or surfaces or curved surfaces with a certain angle with the horizontal plane. However, for convenience of description, the present invention is only described above and below the horizontal surface.

Requirements on the drawstring and its affiliates: ① When welding low-melting metals or alloys, it is best to use a high-strength soft carbon fiber rope (the tensile strength of the domestically produced carbon fiber strength has reached above 5000MPa); when welding When high melting point metal or alloy needs auxiliary heating, or when high-strength carbon fiber rope cannot be used, high-strength flexible steel wire rope can be used. ② After the mixing head and the work plate are installed, the rope should be pre-tensioned. The pulling force of each rope should be equal to the sum of the dry friction resistance of a single shaft and the half of the forward resistance of the stirring needle. This can partially eliminate the effects of the connection gap and elastic deformation of the rope, and maintain this force at normal welding speed. The size of the wire is approximately unchanged; ③ The speeds of the ropes should be equal and equal to the appropriate welding speed.

The principle, characteristics and requirements of the stationary double-axle shoulder friction stir welding head with auxiliary rope device are introduced above. In order to facilitate understanding and implementation, the following specifically takes a straight butt joint with a welding surface as a horizontal plane as an example, and the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a cross-sectional view of a stationary double-axle shoulder friction stir welding head with an auxiliary rope device according to the present invention.

FIG. 2 is a schematic view of the principle view of the front view of a stationary double-axle shoulder friction stir welding head with an auxiliary rope device according to the first aspect of the present invention;

Fig. 3 is a three-dimensional schematic diagram of a shaft shoulder of the stirring head of the present invention

FIG. 4 is a schematic view showing the principle of the front view of a stationary double-axle shoulder friction stir welding head with an auxiliary rope device according to a second aspect of the present invention;

detailed description

For the welding process of medium-thick plates using stationary biaxial shoulder friction stir welding with auxiliary rope device, the present invention must use a commonly used lead-in plate with a keyhole (very familiar to welding technicians, so here (Not shown), please refer to Figs. 1-3, the lead-in plate and the plate 7 to be welded are of equal thickness. The two workpieces should be installed and fixed in butt joints. It should prevent misalignment in the up and down direction, there should be no gap in the width direction and adapt to the butt pressure. Both of these directions should be clamped and fixed. For the assembly and welding process of the stirring head and the rope device, the steps are as follows:

(1) Please refer to Figure 2. At the beginning of the drawstring 14, drawstring 27, first of all, according to the size of the small circular arc in the middle and the two

terminals

13, 18 with threaded ends, it can be easily removed and inserted. And the crimp joints are not less than 3; pull the rope 14 and the rope 27 in a suitable way to the beginning of the weld. The

pull ropes

14, 27 should be identified by color and numbered sleeves for future use. The invention proposes that the material of the drawstrings is preferably high-strength carbon fiber;

(2) Please refer to Figure 1. First insert the stirring pin 1 into the keyhole of the lead-in plate of the plate 7 to be welded, and then place the upper shoulder 6, thrust tapered roller bearing 5, disc spring 4, loose washer 3, and lock. The tightening nut 2 is sequentially inserted from the shank end of the stirring needle 1 (the present invention recommends the use of a Nord-Lock anti-loosening washer, and the bolt will be locked tightly, the same applies hereinafter), and the tightening nut 2 is slightly tightened manually. It is worth noting that there is a clearance fit between the stirring needle 1 and the inner ring of the thrust tapered roller bearing 5, and between the upper shaft shoulder 6 and the outer ring of the thrust tapered roller bearing 5, the adjacent shoulder of the stirring part of the stirring needle 1 The diameter gap between the part and the upper shoulder 6 is about 0.3 to 0.5 mm. The lower shoulder 8, thrust tapered roller bearing 9, disc spring 10, lock washer 11 and lock nut 12 are simply inserted from the tail end of the stirring pin 1 in sequence, which is the same as the previous paragraph of this article and will not be repeated here.

(3) Please refer to Figures 2 to 4. Turn the upper shoulder 6 to a proper position. Pass the terminal 28 with an arc groove in the middle and the thread at the end through the upper ear hole of the shoulder 6. After pulling the knots in advance through the rope 27, screw the terminal 28 into the lower ear hole of the shaft shoulder 6, and the socket is located in the arc groove of the terminal 28. For the lower shaft 8, the rope 14, the wiring The assembling process of the column 13 is the same as that of the upper shoulder 6 and the like mentioned in this article, and will not be repeated here;

(4) Please refer to Figure 1. Tighten the lock nut 2 and lock nut 12 with a torque wrench, which will pre-compress the weldment 7 to make the compression amount reach the value required for upset pressure (based on a large number of tests, the Compression and torque form a corresponding table). Note that the center of the shoulder and the center of the ear hole of the shoulder should be aligned with the weld at the end;

(5) Connect the handle of the stirrer head to the rotating spindle sleeve of the friction stir welding machine and fasten it;

For Figure 2 and Figure 4, the following steps are slightly different between the two, as follows: For Figure 2, following (1) to (5):

(6) Please refer to Figure 2. Connect the

pull ropes

14, 27 through the

tension adjustment devices

17 and 23, and connect the pull rope 19 as shown in Figure 2, and connect the mobile gantry or move through the fixed pulleys 20, 21, 26 The tension adjustment device 24 on the moving base 25 of the platform or welding robot; pull the slide 16 (there are four rollers below) along the guide groove 15 to make the two

ropes

14, 27 straight and in a certain collapsed state, The slide 16 is pressed by a bolt set on the guide groove 15 (this bolt set is not shown). At this time, adjust the two tension adjustment devices 17, 23 (the device has an initial adjustment device, adjustment threads and pressure sensors, etc., and a rectangular opening in the middle of the slide plate 16 is convenient for adjusting the knob device). The tensile force is equal to the sum of the dry friction resistance generated by the friction surface of a single shoulder and the half of the forward resistance generated by the stirring needle itself, and can be moderately larger than this value (this is a consideration of mechanical efficiency) , Loosen the bolt set of the compression slide 22.

(7) By adjusting the tension adjusting device 24, the value of the tension sensor 18 is equal to the sum of the tensions of the two

pull ropes

14, 27, or slightly greater than 2%. It is worth noting that the moving device of the mobile gantry or mobile platform or the mobile base of the welding robot should have sufficient traction capacity, which is at least greater than the movement of the pull rope 14, pull rope 27, and the mobile gantry or mobile platform or welding robot. The sum of the resistance of the base 25 is at least 20%. After turning on the equipment, set the spindle rotation speed of friction stir welding and other appropriate parameters, start the spindle rotation motor of friction stir welding, and then start the mobile gantry or mobile platform or the moving base of the welding robot to make the speed equal to the appropriate speed. And at this time, the stirring needle 1, upper shoulder 6 and lower shoulder 8, mobile gantry or mobile platform or mobile base 25 of the welding robot, the forward speed is equal, when each stationary shaft shoulder runs to the weld When the tail end of the board is drawn out, the welding of the weld can be completed.

For Figure 4, the steps following (1) to (5) are as follows:

(6) Please refer to Figure 4. Connect the

pull ropes

14, 27 through the

tension adjustment devices

17 and 23, and connect the pull rope 32 to the mobile gantry or mobile platform through the fixed pulleys 21, 26, and 29 as shown in Figure 4. Or the wiring device on the moving base of the welding robot and the tension adjustment device 31 on the slide; pull the slide 16 along the guide groove 15 (there are four rollers below), so that the three

ropes

14, 27, 32 are straightened and at a certain level In the collapsed state, the slide plate 16 is pressed by a bolt group on the guide groove 15 (the bolt group is not shown). At this time, adjust the three

tension adjustment devices

17, 23, 31 (the device has an initial adjustment device, an adjustment thread and a pressure sensor, etc., and a rectangular opening in the middle of the slide plate 16 is convenient for adjusting the knob device), so that the pull rope 17 and the pull rope The tensile force of 23 is equal to the sum of the dry friction resistance generated by the friction surface of a single shoulder and the forward resistance of the stirring needle itself caused by the workpiece, and can be moderately larger than this value by 3% (this is due to the consideration of mechanical efficiency Question); make the pulling force of the rope 31 equal to the resistance of the moving gantry or mobile platform or the moving base 25 of the welding robot to move at a constant speed, and can be enlarged by about 5%. Here, the enlargement is slightly for the consideration of mechanical efficiency. It is an estimated value. The specific percentage can be obtained based on experiments. The same applies below. Keep the knob positions of the

tension adjustment devices

17, 23, and 31 unchanged after the adjustment, and loosen the bolt set of the compression slide 22. The length of the slide 16 with the roller is not less than 400-800mm, the side of the guide groove 15 is coated with grease, and the sum of the gaps between the two sides of the slide 16 and the guide groove 15 is not more than 1.0mm. This can ensure that during normal work, each pull It is very important that the force and direction of the ropes do not change greatly, and at the same time, the speeds of the ropes are ensured to the maximum.

(7) By calculating the sum of the pulling forces of the

ropes

14, 27, 32, the resultant force is the pulling force that the rope 19 should have. The calculated pulling force of the rope 19 is obtained, and the motor 30 (a motor that meets constant torque and constant speed, (Including its control equipment, with a hub) in order to make the pull rope 19 maintain the torque value corresponding to the calculated pulling force, or slightly greater than 2%.

(8) Please refer to Fig. 4. After starting the equipment, set the appropriate parameters such as the rotation speed of the main shaft of friction stir welding and the torque value of the motor 30, then start the main shaft rotary motor of friction stir welding, and then start the motor 30 and the motor 30. The speed of the sliding and pulling slide 16 should be equal to the proper welding speed. At this time, the stirring needle 1, the upper shoulder 6 and the lower shoulder 8, the mobile gantry or mobile platform, or the mobile base 25 of the welding robot are all moved along the pull rope 19, and when each stationary shaft shoulder runs to the end of the welding plate The end of the welding can be completed.

So far, the straight-line butt weld has been described with reference to the specific embodiments and processes of FIGS. 1 to 4 of the description.

However, for curved butt welds that are close to a straight line, a multi-degree-of-freedom welding robot with a seam tracking system must be used for welding. As mentioned before, the base of the welding robot is generally moved along the guide rail for welding (there is no gantry at this time) Frame), the base of the robot has an automatic running device; or the welding robot is directly mounted on a gantry with an automatic running device. As for the other steps, it is exactly the same as the straight butt weld, but the welding robot tracking system and the longitudinal force sensor of the stirring needle need to be added. When the longitudinal force sensor detects that the force is greater than the specified value, the stirring head and the The perturbation in the opposite direction can increase the pulling force of the shoulder shoulder rope, but because the forward speed of the base of the welding robot is much faster than the perturbation speed, the combined speed of the stirring needle is still forward, so the stirring needle will not return. go.

However, the key details in the drawings of the description are further explained as follows:

① The invention is suitable for simultaneous welding of two surfaces with a fixed plate thickness (including plate thickness tolerances), and is particularly suitable for butt welds of straight or nearly straight smooth curves of medium-thick plates, which is also applicable to thin plates. After consulting a large amount of literature, for aluminum alloys, a four-plane milling flat mixing needle is better. It is recommended to use it. The material can be hot-working die steel and heat treated. For the stationary shoulder, a completely stationary shoulder can be used. The shoulder of the shaft should be a high-carbon tool after heat treatment. However, for different materials to be welded, different materials should be used for the stirring pin and the stationary shaft shoulder; the dry friction between the stationary shaft shoulder and the surface to be welded, the simple forward resistance of the stirring needle and suitable welding parameters are calculated by theory and A large number of tests are available for use in formal manufacture;

② When the welding seam to be welded is particularly long, each pull rope can be turned 180 degrees again by the fixed pulley set and its supporting device, and the pull rope returns to the vicinity of the welding starting point, so that each of the ropes can move at a constant speed. Can be laid under the ground without taking up space above the ground;

③ The bearing in the present invention is a thrust tapered roller bearing, which does not adopt the bearing fixing method in the traditional machinery. The present invention does not require the bearing to have as long life as in the traditional machinery, and it is not necessary. It just needs to use its structure and function. ;

④ When pulling the mobile gantry or mobile platform or the moving base of the welding robot, the direction of the rope must be parallel to the direction of advance, and the same should always be parallel to the weld on the shoulder; for skateboards, the best arrangement of each rope Make the skateboard not subject to additional torque;

⑤ When the thickness of the plate is not large, the present invention can only use one shaft shoulder rope, that is, only the rope on the tail end of the stirring needle is needed. The rope only bears the force of the shaft shoulder rope, and the stirring needle handle There is no drawstring at the end, and the dry friction resistance between the shaft shoulder of the end and the workpiece and half of the resistance of the stirring needle itself are borne by the stirring needle itself;

⑥ The present invention is not limited to the above embodiments. If various changes or modifications to the present invention do not depart from the spirit and scope of the present invention, if these changes or modifications belong to the claims and equivalent technical scope of the present invention, the present invention These changes or modifications are also intended to be included.

Claims

A static double-axle shoulder friction stir welding head with auxiliary rope pulling device is characterized in that it comprises a static double-axle shoulder friction stir welding head and a set of auxiliary rope-drawing devices. One static shaft shoulder corresponds to one surface and can be simultaneously Butt welds that weld straight and near-straight smooth curves of medium-thick flat plates and curved plates with high quality and efficiency can also be applied to thin plates.

The stationary double-shaft shoulder friction stir welding head includes: a stirring pin, 2 shaft shoulders, 2 thrust tapered roller bearings, 2 disc springs, 2 lock washers, and 2 lock nuts.

The auxiliary rope device includes several carbon fiber ropes (or high-strength and flexible steel wire ropes) containing pressure joints, several binding posts, several tension adjustment devices containing pressure sensors, a slide plate, its guide groove, and a pressure plate. Bolt set, an independent motor, a set of fixed pulleys, several pressure sensors with adjustment devices, etc. The middle part of the binding post contains a circular arc groove, which is convenient for positioning the knot of the drawstring;

When welding smooth butt welds that are close to a straight line, a multi-degree-of-freedom friction stir welding robot with a seam tracking system, a force sensor that detects the longitudinal force of the stirring pin, etc. are required.
The auxiliary rope device according to claim 1, the shoulder side of the skateboard must have two outside shoulder ropes, and according to who ultimately drives these two shoulder ropes, there are 2 different schemes: Scheme 1 is The mobile gantry or mobile platform or the mobile base of the welding robot is connected to the non-axis shoulder side of the skateboard through a pull rope and a fixed pulley set. The walking device on the mobile gantry or the mobile platform or the mobile robot's mobile base finally drives the slide. And 2 axle shoulder ropes and 2 axle shoulders to advance together; Option 2 is a mobile gantry or a mobile platform or a mobile robot welding base, which is connected to the axle shoulder side of the skateboard through a rope and a fixed pulley set. The rope drives the skateboard, and finally drives the two shoulder and shoulder ropes, the two shoulders, the stirring pin, and the mobile gantry or mobile platform or the mobile base of the welding robot forward together. In both solutions, two shoulder ropes, two shoulders, agitating needles, and a moving gantry or mobile platform or the moving base of a welding robot can move together at a uniform speed, and this speed is the appropriate welding speed.
The auxiliary rope device according to claims 1 to 2, wherein the two shoulder ropes on the shoulder side are subjected to a pulling force equal to the dry friction resistance generated by the single shoulder friction surface, and the stirring needle itself is generated by the workpiece. Of the half of the forward resistance, and the pull rope connected to the mobile gantry or mobile platform or the mobile base of the welding robot has a pulling force equal to the horizontal force that pulls the mobile base at a constant speed; Only one pull rope is needed, and its pull force is equal to the sum of all pull ropes on the shoulder side of the skateboard shaft.
The slide of the auxiliary rope device according to claims 1 to 3, the function of the slide in the guide groove is very simple and clever to ensure that the speed of each rope on the shoulder side of the slide shaft is equal and that each rope should have pull;
A method for simultaneously butt welding a straight line and a smooth curve close to a straight line on both surfaces of a flat plate and a curved plate by using the stirring head according to claim 1, comprising steps S1 to S4

S1: Provide the facilities, equipment and parts of claims 1 to 4, install the stirring head and the workpiece in place, fix the workpiece, and connect the handle of the stirring head to the rotary spindle of friction stir welding;

S2: Pull the slide to make each rope straight and in a certain collapsed state. Press the slide through the bolt set on the guide groove. At this time, adjust the tension adjustment device to make the tension of the shaft shoulder rope Is equal to the sum of the dry friction resistance generated by the friction surface of a single shoulder and the half of the forward resistance generated by the stirring needle itself by the workpiece, and can be moderately larger than this value; for the traction of a mobile gantry or mobile platform or the mobile base of a welding robot The forward pulling rope, the pulling force of the pulling rope is always equal to or slightly greater than 5% of the moving resistance of the moving gantry or mobile platform or the moving base of the welding robot (this operation is only performed if there is the pulling rope). Keep the knob position of the tightening knob device after adjustment unchanged, and loosen the bolt group that presses the slide;

S3: According to the different facilities, equipment and parts, this step has two ways:

Approach 1: When the drawstring on the non-shoulder side of the skateboard is connected to the mobile gantry or mobile platform with its own running device or the mobile base of the welding robot through the fixed pulley set, adjust the tension adjustment device to make the non-shoulder side of the skateboard The pull force of the pull rope is equal to the sum of the pull forces of the pull ropes on the shoulder side of the skateboard shaft, and can be moderately larger than this value by 5% (considering mechanical efficiency). Turn on each device, set the proper spindle rotation speed for friction stir welding, and set the appropriate forward speed of the mobile gantry or mobile platform or the mobile base of the welding robot (this speed is the appropriate welding speed). The rotation of the main shaft of the friction stir welding machine starts to rotate, and then the traveling device of the mobile gantry or mobile platform or the mobile base of the welding robot starts to move at a constant speed at a set speed, which drives the slide and each rope to complete the welding. Welding.

Path 2: When there is a pull rope for the forward movement of the gantry or mobile platform or the moving base of the welding robot on the shaft and shoulder side of the skateboard, by calculating the sum of the pull forces of the shaft and shoulder ropes on the shaft and shoulder side of the skateboard, the resultant force is the skateboard The pulling force of the non-shoulder side rope should be calculated by the motor to maintain the corresponding torque value of the calculated rope. Turn on the equipment and set appropriate parameters such as the rotational speed of the main shaft of friction stir welding and the torque value of the motor, start the rotary main shaft of friction stir welding, and then start the motor. The speed of the slide plate pulled by the rotation of the motor by pulling the rope should be equal to the appropriate speed. The welding speed can make the systems move at a constant speed. When each stationary shaft shoulder drives out of the welding lead-out board, the welding of the welding can be completed.

S4. For smooth curved butt welds that are close to a straight line, a multi-degree-of-freedom welding robot needs to be added on the basis of S3. The robot is required to have a welding seam tracking system and a longitudinal force sensor of the stirring pin (can be installed on a suitable arm of the welding robot) (Above), when the longitudinal force sensor detects that the force value is greater than the specified value, the perturbation of the stirring needle in the opposite direction to the forward direction should be used to increase the pulling force of the shoulder shoulder rope, but the forward speed of the base of the welding robot is much higher At this perturbation speed, the combined speed of the stirring needle is still forward, and the stirring needle will not go back.